In recent years, the increase in LED output has been achieved. Following it, LED devices using LED bare chips being semiconductor components have been used also in general illumination, car headlamps, and so on which require large quantities of light. However, since the LED device also consumes large power for obtaining a large quantity of light, there has arisen a problem of heat generation which occurs as a result of the large power consumption. That is, since the LED bare chip is weak against heat, it is necessary to effectively dissipate the heat particularly from the bare chip.
JP-A-2004-199896 (Patent Document 1) discloses an LED illumination system which is increased in heat dissipation. This LED illumination system will be briefly described with reference to FIG. 24. A heat transfer layer 2 made of diamond is provided on a substrate 1, a conductive layer 3 having predetermined patterns is formed on the heat transfer layer 2, LED chips 4 are placed at predetermined positions on the conductive layer 3, electrodes 7 and 8 of the LED chips 4 are electrically connected to terminals 5 and 6 of the conductive layer 3, and lower surfaces of the LED chips 4 are in contact with heat contact portions 9 of the conductive layer 3, thereby enhancing heat dissipation.